Positive electrode mixture precursor and production method therefor

Abstract

A positive electrode mixture precursor containing a sulfur-based active material, a porous carbon material, and at least one of an ion conductor and a variant of said ion conductor, wherein the sulfur-based active material is present in at least part of the interior and exterior of the carbon material, and at least part of the ion conductor and the variant of said ion conductor covers at least part of the sulfur-based active material.

Description

Positive electrode composite precursor and method for producing the same

[0001] The present invention relates to a cathode mixture precursor and a manufacturing method thereof, and more particularly to a cathode mixture precursor and a cathode mixture capable of improving the charge-discharge characteristics of a lithium ion battery, and a manufacturing method thereof.

[0002] Lithium-ion batteries require high battery capacity. To improve battery capacity, the use of sulfur in the cathode has been investigated due to its large theoretical capacity. However, sulfur has low lithium ion and electronic conductivity, so when sulfur is used in the cathode, it is necessary to ensure the lithium ion and electronic conductivity within the cathode.

[0003] To address the above-mentioned issues, a cathode composite has been investigated in which sulfur, a carbon material, diphosphorus pentasulfide, a solid electrolyte, etc. are mechanically mixed in a planetary ball mill to form a composite (see, for example, Patent Documents 1 and 2). Also, a cathode composite has been investigated in which sulfur, a carbon material having pores, and a solid electrolyte are combined, with the solid electrolyte being placed in the pores of the carbon material from a solution state (see, for example, Patent Documents 3 and 4).

[0004] Patent No. 7156157 Patent No. 6061139 Patent No. 7283657 International Publication No. 2023 / 187466

[0005] There is a demand for further improvement in charge-discharge characteristics compared to conventional techniques. Conventional mechanical mixing (mechanical milling) methods, such as those described in Patent Documents 1 and 2, result in insufficient interface formation between the sulfur and carbon material in the resulting composite and the solid electrolyte, diphosphorus pentasulfide, or the like, limiting the formation of an ion conduction path between the sulfur and the carbon material. Techniques for precipitating a solid electrolyte from a solution, such as those described in Patent Documents 3 and 4, result in insufficient interface formation between the sulfur and carbon material in the resulting composite and the solid electrolyte, limiting the formation of an ion conduction path between the sulfur and the carbon material. One object of the present invention is to provide a cathode composite precursor and a cathode composite that can improve the charge-discharge characteristics of lithium-ion batteries.

[0006] As a result of intensive research, the present inventors have found that in the production of a positive electrode composite, the charge-discharge characteristics of the final product, a lithium-ion battery, can be improved by previously preparing a precursor by mixing a mixture or composite of a sulfur-based active material and a carbon material with a molten ion conductor, and have completed the present invention.

[0007] According to the present invention, the following positive electrode mixture precursors and the like are provided. 1. A positive electrode mixture precursor comprising a sulfur-based active material, a carbon material having micropores, and at least one of an ion conductor and a modified form of the ion conductor, the sulfur-based active material being present at least partially inside and outside the carbon material, and at least a portion of the ion conductor and the modified form of the ion conductor coating at least a portion of the sulfur-based active material. 2. The positive electrode mixture precursor according to 1, which satisfies at least one of the following formulas (1) and (2) in a P2p spectrum in surface elemental analysis by X-ray photoelectron spectroscopy. Ａ / I Ｂ >0.8 (1) I Ｃ / I Ｂ >0.8 (2) (wherein, I Ａ is the signal intensity at position A where the binding energy is around 135.4 eV, I Ｂ is the signal intensity at position B where the binding energy is around 134.25 eV, I Ｃ is the signal intensity at position C where the binding energy is around 133.0 eV.) 3. Ａ / I Ｂ and I Ｃ / I Ｂ4. The cathode mixture precursor according to 2, wherein at least one of the above is 1.0 or more. 4. The cathode mixture precursor according to 1, wherein the elemental ratio C / P of carbon element to phosphorus element is 20 or less by surface elemental analysis by X-ray photoelectron spectroscopy. 5. The cathode mixture precursor according to 1, wherein the main component occupancy is 95.0% or more in element mapping image analysis by energy dispersive X-ray spectroscopy of a scanning electron microscope image. 6. The cathode mixture precursor according to any one of 1 to 5, wherein the mass ratio of the total of the sulfur-based active material, ionic conductor, and modified ionic conductor to the carbon material is less than 5.00. 7. The cathode mixture precursor according to any one of 1 to 6, wherein the melting point of the ionic conductor is 130°C to 450°C. 8. The cathode mixture precursor according to any one of 1 to 7, wherein the ionic conductor is a lithium ion conductive material containing one or more elements selected from lithium, boron, oxygen, and phosphorus, or a precursor thereof. 9. 10. The cathode mixture precursor according to any one of 1 to 8, wherein the ion conductor comprises phosphorus sulfide. 11. The cathode mixture precursor according to any one of 1 to 9, wherein the ion conductor comprises diphosphorus pentasulfide. 12. The cathode mixture precursor according to any one of 1 to 10, wherein the sulfur-based active material comprises elemental sulfur. 13. The method according to 12, wherein at least one of a composite and a mixture of a sulfur-based active material and a carbon material having pores is mixed with an ion conductor in a molten state. 14. The method according to 12 or 13, wherein the mass ratio of the total of the sulfur-based active material and the ion conductor to the carbon material is less than 5.00. 15. The method according to any one of 12 to 14, wherein the melting point of the ion conductor is 130°C to 450°C. 16. The manufacturing method according to any one of 12 to 15, wherein the ion conductor is a lithium ion conductive material containing one or more elements selected from lithium, boron, oxygen, and phosphorus, or a precursor thereof. 17. The manufacturing method according to any one of 12 to 16, wherein the ion conductor contains phosphorus sulfide. 18. The manufacturing method according to any one of 12 to 17, wherein the ion conductor contains diphosphorus pentasulfide. 19. The manufacturing method according to any one of 12 to 18, wherein the sulfur-based active material contains elemental sulfur. 20. A positive electrode composite comprising the positive electrode composite precursor according to any one of 1 to 11.21. The cathode mixture according to 20, further comprising a solid electrolyte. 22. A cathode comprising the cathode mixture according to 20 or 21. 23. A lithium ion battery comprising the cathode mixture according to 20 or 21 or the cathode of 22.

[0008] The present invention provides a cathode composite precursor and a cathode composite that can improve the charge-discharge characteristics of lithium-ion batteries. Furthermore, the amount of solid electrolyte used, which is often produced through a complex manufacturing process, can be reduced, which is expected to result in cost savings.

[0009] 1 shows a P2p spectrum of Example 1. FIG. 2 shows a P2p spectrum of Example 2. FIG. 3 shows a P2p spectrum of Example 3. FIG. 4 shows a P2p spectrum of Example 5. FIG. 6 shows a P2p spectrum of Example 6. FIG. 7 shows a P2p spectrum of Comparative Example 2. FIG. 8 shows an S2p spectrum of Example 1. FIG. 9 shows an S2p spectrum of Example 2. FIG. 10 shows an S2p spectrum of Comparative Example 2. (a) is image data obtained by superimposing EDS mappings of C, P, and S in Example 1, and (b) is an image obtained by image processing of (a). (a) is image data obtained by superimposing EDS mappings of C, P, and S in Example 2, and (b) is an image obtained by image processing of (a). (a) is image data obtained by superimposing EDS mappings of C, P, and S in Comparative Example 2, and (b) is an image obtained by image processing of (a). (a) is image data in which EDS mappings of C, P, and S of Comparative Example 3 are superimposed, and (b) is an image obtained by image processing of (a). FIG. 1 is an X-ray diffraction (XRD) chart of Example 1. FIG. 2 is an XRD chart of Example 2. FIG. 3 is an XRD chart of Comparative Example 2. FIG. 4 is an XRD chart of Comparative Example 3. FIG. 5 is an XRD chart of the solid of Example 1. ３１ 1 shows the results of waveform separation of the P-NMR spectrum. ３１ This is the result of waveform separation of the P-NMR spectrum.

[0010] A positive electrode composite precursor according to one embodiment of the present invention includes a sulfur-based active material, a carbon material having micropores, and at least one of an ion conductor and a modified version of the ion conductor (hereinafter, the ion conductor and the modified version of the ion conductor may be collectively referred to as "ion conductors"). The sulfur-based active material is present at least partially inside and outside the carbon material, and at least a portion of the ion conductor coats at least a portion of the sulfur-based active material.

[0011] The embodiment in which "at least a portion of the ionic conductor coats at least a portion of the sulfur-based active material" can be achieved, for example, by providing a process for mixing a molten ionic conductor with at least one of a composite and a mixture of a sulfur-based active material and a porous carbon material during the production of a cathode composite precursor. By mixing the molten ionic conductor with the composite and mixture, the surface of the sulfur-based active material and / or carbon material is coated with the liquid ionic conductor. After cooling after the mixing process, a structure is formed in which the ionic conductor coats the surface of the sulfur-based active material and / or carbon material. The ionic conductor coating structure is a new structure that cannot be formed by conventional mechanical mixing (mechanical milling). The ionic conductor coating structure forms a strong interface between the sulfur-based active material and the carbon material, resulting in improved ionic conductivity to the sulfur-based active material and the carbon material, and promoting the reaction of the sulfur-based active material, which is thought to improve charge / discharge characteristics.

[0012] The state in which "at least a portion of the ion conductor covers at least a portion of the sulfur-based active material" can be confirmed by various analyses. The positive electrode composite precursor of the present invention can be expressed, for example, as any of (A1) to (A10) below.

[0013] (A1) In a P2p spectrum obtained by surface elemental analysis using X-ray photoelectron spectroscopy, at least one of the following formulas (1) and (2) is satisfied: Ａ / I Ｂ >0.8 (1) I Ｃ / I Ｂ >0.8 (2) (wherein, I Ａ is the signal intensity at position A where the binding energy is around 135.4 eV, IＢ is the signal intensity at position B where the binding energy is around 134.25 eV, I Ｃ is the signal intensity at position C where the binding energy is near 133.0 eV.) Note that "near" means that the position of the binding energy may vary slightly depending on the measurement device, etc., but for example, position A means a peak that appears in the range of 135.0 eV or more and 136.5 eV or less, position B means a peak that appears in the range of 133.5 eV or more and less than 135.0 eV, and position C means a peak that appears in the range of 132.0 eV or more and less than 133.5 eV. Also, if no clear peak appears at each position, 135.4 eV is position A, 134.25 eV is position B, and 133.0 eV is position C. In one embodiment, I Ａ / I Ｂ is preferably 1.0 or more, more preferably 1.1 or more, and particularly preferably 1.2 or more. Ｃ / I Ｂ is preferably 1.0 or more, more preferably 1.1 or more, and particularly preferably 1.2 or more. Ａ / I Ｂ and I Ｃ / I Ｂ There is no upper limit to the value, but it is, for example, 5.0 or less.

[0014] (A2) The element ratio C / P of carbon to phosphorus is 20 or less as determined by surface elemental analysis using X-ray photoelectron spectroscopy.

[0015] (A3) In elemental mapping image analysis of a scanning electron microscope image by energy dispersive X-ray spectroscopy, the occupancy rate of the main component is 95.0% or more.

[0016] (A4) The rate of change in the carbon to phosphorus element ratio C / P before and after GCIB treatment, as determined by surface elemental analysis using X-ray photoelectron spectroscopy, is 0.95 or more.

[0017] (A5) The rate of change in the carbon to phosphorus element ratio C / P before and after Ar sputtering, as determined by surface elemental analysis using X-ray photoelectron spectroscopy, is 0.4 or more.

[0018] (A6) The positive electrode composite precursor contains a sulfur-based active material, a carbon material having micropores, and phosphorus sulfide, and is a solid ３１In the P-NMR measurement, P ２ S ５ The area ratio of the peak is 60% or less.

[0019] (A7) The positive electrode composite precursor contains a sulfur-based active material, a carbon material having micropores, and phosphorus sulfide, and is a solid ３１ In the P-NMR measurement, P ２ S ６ ４－ , P ２ S ７ ４－ and P.S. ４ ２－ The total area ratio of the peaks is 30% or more.

[0020] (A8) The specific surface area of ​​the positive electrode composite precursor is 7.5 m ２ / g or less.

[0021] (A9) As a result of X-ray diffraction measurement, the ionic conductor and the modified ionic conductor are amorphous.

[0022] (A10) In the S2p spectrum in the surface elemental analysis by X-ray photoelectron spectroscopy, the area of ​​the PSx peak and S ８ The ratio of the peak areas (S ８ Peak / PSx peak) is 15 or less.

[0023] The above (A1) to (A10) each independently represent one embodiment of the cathode composite precursor of the present invention. Furthermore, the above (A1) to (A10) can also be arbitrarily combined to specify the cathode composite precursor of the present invention. The measurement methods for the above (A1) to (A10) will be described in the Examples below.

[0024] In one embodiment, the positive electrode composite precursor does not contain any solid electrolyte other than the ion conductor and the modified ion conductor, specifically, it does not substantially contain the Li element contained in the solid electrolyte.

[0025] In one embodiment, the mass ratio of the sulfur-based active material (S), the ionic conductor containing elemental phosphorus, and the modified ionic conductor to the carbon material (C) is less than 5.00. For example, when the ionic conductor is diphosphorus pentasulfide, the mass ratio [(S + P ２ S ５) / C] is smaller than 5.00. When the mass ratio is less than 5.00, the charge / discharge characteristics are further improved. The mass ratio may be 4.80 or less, 4.50 or less, 4.30 or less, 4.00 or less, 3.70 or less, or 3.50 or less. The mass ratio can be adjusted by the amount of each constituent material.

[0026] The positive electrode mixture precursor of the present invention can be obtained, for example, by a production method including a step of mixing at least one of a composite and a mixture of a sulfur-based active material and a porous carbon material with a molten ion conductor.

[0027] The sulfur-based active material is not particularly limited, but sulfur, lithium sulfide (Li ２ S), lithium polysulfide (Li ２ S ｎ : n satisfies 1<n≦8.), titanium sulfide (TiS ２ ), molybdenum sulfide (MoS ２ ), iron sulfide (FeS, FeS ２ ), copper sulfide (CuS), nickel sulfide (Ni ３ S ２ ), sulfur-containing polymer compounds, etc. Among these, sulfur is preferred. There are no particular limitations on the sulfur, but sulfur with a high purity is preferred. Specifically, the purity is preferably 95% by mass or more, more preferably 96% by mass or more, and particularly preferably 97% by mass or more. Examples of the crystal system of sulfur include α sulfur (orthorhombic system), β (monoclinic system), γ (monoclinic system), amorphous sulfur, etc. These can be used alone or in combination of two or more types.

[0028] Examples of ion conductors include lithium ion conductive materials containing one or more elements selected from lithium, boron, oxygen, phosphorus, halogens, and antimony, or precursors thereof. Preferably, the present invention includes a lithium ion conductive material containing one or more elements selected from lithium, boron, oxygen, and phosphorus, or precursors thereof. In this specification, a "lithium ion conductive material containing one or more elements selected from lithium, boron, oxygen, phosphorus, halogens, and antimony" refers to a material that remains solid at 25°C under a nitrogen atmosphere and has ionic conductivity attributable to lithium ions. Furthermore, a "precursor of a lithium ion conductive material containing one or more elements selected from lithium, boron, oxygen, phosphorus, halogens, and antimony" refers to a material that, when used as an active material in a lithium ion battery, reacts with lithium metal or lithium ions to form a lithium-containing compound, thereby becoming the lithium ion conductive material.

[0029] As used herein, the term "halogen" includes elements such as fluorine, chlorine, bromine, and iodine.

[0030] Since the ionic conductor is heated to form a melt, the melting point is preferably 130 to 450°C, and more preferably 220 to 450°C. Furthermore, the melting point of the ionic conductor is preferably lower, such as 440°C or lower, 430°C or lower, 420°C or lower, 410°C or lower, or 400°C or lower. Elemental sulfur, which is an example of a sulfur-based active material, has a boiling point of approximately 450°C. Mixing it with a melt of a substance having a melting point higher than this will volatilize the material, and it is believed that the desired positive electrode composite precursor cannot be obtained. Furthermore, lowering the temperature in the process reduces the energy required for production, leading to lower costs.

[0031] Lithium ion conductive material: lithium borohydride, LiBF ４ , organic lithium salts, polymer electrolytes such as polyethylene oxide, etc. Precursors of lithium ion conductive materials include phosphorus sulfides such as diphosphorus pentasulfide, red phosphorus, boron sulfide, diphosphorus pentoxide, tin, etc. These compounds may be used alone or in combination of two or more.

[0032] Examples of organic lithium salts include bis(perfluoroalkylsulfonyl)imide lithium salts such as bis(trifluoromethanesulfonyl)imide lithium, bis(fluorosulfonyl)imide lithium, fluorosulfonyl-trifluoromethanesulfonylimide lithium, bis(pentafluoroethanesulfonyl)imide lithium, and bis(nonafluorobutanesulfonyl)imide lithium; lithium salts of perfluoroalkylsulfonimides such as 4,4,5,5-tetrafluoro-1,3,2-dithiazolidine-1,1,3,3-tetraoxide lithium salt; lithium salts of fluorosulfonylimides; lithium carboxylic acid salts such as trifluoromethanesulfonic acid, lithium acetate, lithium propionate, and lithium butyrate; lithium organic sulfonates such as lithium dodecylbenzenesulfonate and lithium p-styrenesulfonate; and lithium organic phosphates. These organic lithium salts are also preferably used together with ion-conductive polymers and ionic liquids, as they are expected to provide higher lithium conductivity.

[0033] The ionic conductor is preferably one or more compounds selected from the group consisting of phosphorus sulfide, red phosphorus, boron sulfide, diphosphorus pentoxide, and polymer electrolytes such as polyethylene oxide, which are substantially free of lithium element. Ionic conductors that are substantially free of lithium element are considered to have high affinity with sulfur-based active materials and carbon materials.

[0034] More preferably, the ionic conductor is one or more compounds containing phosphorus selected from the group consisting of phosphorus sulfide, red phosphorus, and diphosphorus pentoxide. ４ S ３ ), diphosphorus pentasulfide (P ２ S ５ ), phosphorus heptasulfide (P ４ S ７ ), tetraphosphorus pentasulfide (P ４ S ５) and the like. Furthermore, phosphorus sulfide may have a dimer or polysulfide structure, or may be a mixture. Particularly preferred is diphosphorus pentasulfide, which is expected to react with lithium to form a sulfide solid electrolyte exhibiting high ionic conductivity. The content of phosphorus sulfide or diphosphorus pentasulfide relative to the entire ionic conductor is 50% by mass or more, 80% by mass or more, 95% by mass or more, or 99% by mass or more, and is substantially 100% by mass. When it is substantially 100% by mass, it may contain unavoidable impurities.

[0035] Examples of carbon materials having micropores include carbon black such as Ketjen black, acetylene black, Denka black, thermal black, channel black, and Knobel (registered trademark), graphite, activated carbon, etc. These may be used alone or in combination of two or more.

[0036] In one embodiment, the BET specific surface area of ​​the carbon material is 50 m ２ / g or more, 6000m ２ This allows a wide contact interface between the carbon material and the sulfur-based active material to be formed, improving the utilization rate of the sulfur-based active material. ２ / g or more, 100m ２ / g or more, 1000m ２ / g or more, 1500m ２ / g or more, 2000m ２ / g or more, 2500m ２ / g or more or 3000m ２ / g or more. ２ / g or less, and more preferably 5000m ２ / g or less is preferred.

[0037] In addition, the pore volume of the carbon material is 0.5 cm ３ / g or more, 6cm ３ This allows the sulfur-based active material to be impregnated into the pores of the carbon material, further improving the battery capacity. ３ / g or more, and more preferably 1.0 cm ３ / g or more is preferable. ３ / g or less, and more preferably 5.0 cm ３ / g or less is preferred.

[0038] In the present invention, the BET specific surface area and pore volume can be determined using a nitrogen adsorption isotherm obtained by adsorbing nitrogen gas to a carbon material at liquid nitrogen temperature. Specifically, the BET specific surface area can be calculated by the Brenauer-Emmet-Telle (BET) multipoint method using the nitrogen adsorption isotherm. Furthermore, the pore volume can be determined by the Barret-Joyner-Halenda (BJH) method using the nitrogen adsorption isotherm. As a measuring device, for example, a specific surface area / pore distribution measuring device (Autosorb-3) manufactured by Quantacrome can be used for the measurement.

[0039] In the manufacturing method of this embodiment, at least one of the composite and mixture of the sulfur-based active material and the carbon material having pores is mixed with a molten ion conductor. In one embodiment, a composite of the sulfur-based active material and the carbon material having pores is prepared in advance, and then the composite is mixed with the molten ion conductor. As a result, the ion conductor is coated on the surface of the composite, i.e., on both the sulfur-based active material and the carbon material, and an ion conduction path between the three is efficiently formed. On the other hand, when a mixture of the sulfur-based active material and the carbon material having pores is mixed with a molten ion conductor, it is believed that the sulfur-based active material, which has a lower melting point than the ion conductor, melts first, thereby forming a composite of the sulfur-based active material and the carbon material having pores, and then the ion conductor melts, thereby forming a similar structure.

[0040] In one embodiment, the mass ratio of the sulfur-based active material (S) to the carbon material (C) is 1:9 to 9:1, preferably 5:5 to 9:1.

[0041] The method for compounding the sulfur-based active material and the carbon material having pores is not particularly limited. For example, the sulfur-based active material and the carbon material may be mixed and crushed using a mixer / crusher such as a planetary ball mill to compound them, or the sulfur-based active material and the carbon material may be heated in a sealed state to a temperature equal to or higher than the melting point of the sulfur-based active material to compound them.

[0042] At least one of the composite and mixture of the sulfur-based active material and the porous carbon material can be mixed with the molten ionic conductor by heating at a temperature equal to or higher than the melting point of the ionic conductor. The heating temperature is adjusted according to the ionic conductor used. Substances that are sublimable at normal pressure can be mixed in a molten state by applying pressure. The heating time is preferably 10 minutes to 24 hours. A positive electrode composite precursor is obtained by cooling after heating. If necessary, a pulverization step may be performed after cooling.

[0043] In one embodiment, the mass ratio of the sulfur-based active material, the carbon material, and the ionic conductor in the positive electrode composite precursor satisfies the following relationship: (sulfur-based active material + carbon material): ionic conductor = 50:1 to 80, preferably (sulfur-based active material + carbon material): ionic conductor = 50:5 to 60.

[0044] In one embodiment, the mass ratio of the total of the sulfur-based active material (S) and the ionic conductor to the carbon material (C) is less than 5.00. For example, when the ionic conductor is diphosphorus pentasulfide, the mass ratio [(S + P ２ S ５ ) / C] is smaller than 5.00. When the mass ratio is less than 5.00, the charge / discharge characteristics are further improved. The mass ratio may be 4.80 or less, 4.50 or less, 4.30 or less, 4.00 or less, 3.70 or less, or 3.50 or less. The mass ratio may be 2.00 or more, 2.60 or more, or 3.20 or more. The mass ratio can be adjusted by the amount of each constituent material.

[0045] The cathode composite precursor of the present invention can be used as a constituent material for lithium ion batteries. For example, the cathode composite precursor of the present invention itself can be used for a cathode composite and a positive electrode. Furthermore, a solid electrolyte can be further blended with the cathode composite precursor of the present invention to form a cathode composite. The solid electrolyte is not particularly limited, but examples thereof include sulfide solid electrolytes used in lithium ion batteries, which will be described later.

[0046] The mixing of the cathode composite precursor and the solid electrolyte is not particularly limited and can be adjusted according to the characteristics of the solid electrolyte used. For example, if the solid electrolyte is crystalline and maintaining the crystallinity affects performance, the mixing of the cathode composite precursor and the solid electrolyte is carried out with a relatively weak force. On the other hand, if the performance of the solid electrolyte does not deteriorate even when mixed and pulverized, it is preferable to mix with a relatively strong force because this increases the number of contact points between the cathode composite precursor and the solid electrolyte. Furthermore, the mixing may be carried out in two or more stages. Examples of devices for mixing the cathode composite precursor and the solid electrolyte include a planetary ball mill, a tumbling mill, a bead mill, a Filmix, a Nauta mixer, a tornado mixer, a twin-screw extruder, a multi-screw roller, and a solid-phase shear kneader.

[0047] A lithium ion battery according to one embodiment of the present invention includes the above-described cathode composite precursor of the present invention. For example, an all-solid-state lithium ion battery can be manufactured by using a solid electrolyte instead of a liquid electrolyte. By using the cathode composite precursor of the present invention, an all-solid-state lithium ion battery with good charge / discharge characteristics can be manufactured. The all-solid-state lithium ion battery will now be described. An all-solid-state lithium ion battery is primarily composed of a cathode layer, an anode layer, and an electrolyte layer, and the cathode composite precursor of the present invention is suitable as a constituent material for the cathode layer. The anode layer and electrolyte layer can be manufactured by known methods. In addition to the cathode layer, anode layer, and electrolyte layer, a current collector is preferably used, and known current collectors can also be used.

[0048] The solid electrolyte is not particularly limited, but examples thereof include sulfide solid electrolytes. The sulfide solid electrolyte is a solid electrolyte that contains at least sulfur atoms and exhibits ionic conductivity due to the lithium ions contained therein. In addition to sulfur atoms, the solid electrolyte preferably contains lithium atoms and phosphorus atoms, more preferably contains lithium atoms, phosphorus atoms, and halogen atoms, and has ionic conductivity due to lithium atoms. The sulfide solid electrolyte may be an amorphous sulfide solid electrolyte or a crystalline sulfide solid electrolyte.

[0049] (Amorphous sulfide solid electrolyte) The amorphous sulfide solid electrolyte can be used without any particular limitation as long as it contains at least sulfur atoms and exhibits ionic conductivity due to the lithium ions contained therein. Representative examples include Li ２ S-P ２ S ５ a solid electrolyte containing sulfur atoms, lithium atoms, and phosphorus atoms, which is composed of lithium sulfide and phosphorus sulfide such as Li; ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ -LiI-LiBr, etc., a solid electrolyte composed of lithium sulfide, phosphorus sulfide, and lithium halide; ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ -P ２ S ５ In order to obtain higher ionic conductivity, a solid electrolyte such as Li ２ S-P ２ S ５ - LiI, Li ２ S-P ２ S ５ -LiCl, Li ２ S-P ２ S ５ - LiBr, Li ２ S-P ２ S ５ A solid electrolyte composed of lithium sulfide, phosphorus sulfide, and lithium halide, such as LiI-LiBr, is preferred. The types of elements constituting the amorphous sulfide solid electrolyte can be confirmed, for example, by an ICP emission spectrometer.

[0050] The amorphous sulfide solid electrolyte contains at least Li２ S-P ２ S ５ When Li ２ S and P ２ S ５ From the viewpoint of obtaining high chemical stability and higher ionic conductivity, the molar ratio of Li to Li is preferably 65 to 85:15 to 35, more preferably 70 to 80:20 to 30, and even more preferably 72 to 78:22 to 28. ２ S-P ２ S ５ In the case of -LiI-LiBr, the total content of lithium sulfide and diphosphorus pentasulfide is preferably 60 to 95 mol%, more preferably 65 to 90 mol%, and even more preferably 70 to 85 mol%. The ratio of lithium bromide to the total of lithium bromide and lithium iodide is preferably 1 to 99 mol%, more preferably 20 to 90 mol%, even more preferably 40 to 80 mol%, and particularly preferably 50 to 70 mol%.

[0051] When the amorphous sulfide solid electrolyte contains lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms, the compounding ratio (molar ratio) of these atoms is preferably 1.0 to 1.8: 1.0 to 2.0: 0.1 to 0.8: 0.01 to 0.6, more preferably 1.1 to 1.7: 1.2 to 1.8: 0.2 to 0.6: 0.05 to 0.5, and even more preferably 1.2 to 1.6: 1.3 to 1.7: 0.25 to 0.5: 0.08 to 0.4. Furthermore, when bromine and iodine are used in combination as halogen atoms, the compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, bromine atoms, and iodine atoms is preferably 1.0 to 1.8: 1.0 to 2.0: 0.1 to 0.8: 0.01 to 0.3: 0.01 to 0.3, more preferably 1.1 to 1.7: 1.2 to 1.8: 0.2 to 0.6: 0.02 to 0.25: 0.02 to 0.25, more preferably 1.2 to 1.6: 1.3 to 1.7: 0.25 to 0.5: 0.03 to 0.2: 0.03 to 0.2, and even more preferably 1.35 to 1.45: 1.4 to 1.7: 0.3 to 0.45: 0.04 to 0.18: 0.04 to 0.18. By setting the compounding ratio (molar ratio) of lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms within the above range, it becomes easier to obtain a solid electrolyte having a thiolisiconregion II type crystal structure described below and having higher ionic conductivity.

[0052] The shape of the amorphous sulfide solid electrolyte is not particularly limited, but may be, for example, particulate. The average particle diameter (D ５０ ) can be, for example, in the range of 0.01 μm to 500 μm, or 0.1 μm to 200 μm. ５０ ) is the particle size at which 50% of the total particle size is reached when the particle size distribution integral curve is drawn and the integral is calculated from the smallest particle size, and the volume distribution is an average particle size that can be measured using, for example, a laser diffraction / scattering particle size distribution measuring device.

[0053] (Crystalline sulfide solid electrolyte) The crystalline sulfide solid electrolyte may be, for example, a so-called glass ceramic obtained by heating the amorphous sulfide solid electrolyte to a temperature equal to or higher than the crystallization temperature, and a sulfide solid electrolyte having the following crystal structure may be used. Examples of crystal structures that the crystalline sulfide solid electrolyte containing lithium atoms, sulfur atoms, and phosphorus atoms may have include Li ３ P.S. ４ Crystal structure, Li ４ P ２ S ６ Crystal structure, Li ７ P.S. ６ Crystal structure, Li ７ P ３ S １１ Examples of such a crystal structure include a crystal structure having peaks at 2θ=approximately 20.2° and 23.6° (for example, JP 2013-16423 A).

[0054] The crystalline sulfide solid electrolyte containing lithium atoms, sulfur atoms, phosphorus atoms, and halogen atoms may have a crystalline structure such as Li ４－ｘ Ge １－ｘ P ｘ S ４ Thio-LISICON Region II crystal structure (Kanno et al., Journal of the Electrochemical Society, 148(7)A742-746(2001)), Li ４－ｘ Ge １－ｘ P ｘ S ４ Examples of the thio-lisicon region II crystal structure include those having a crystal structure similar to the thio-lisicon region II type (see Solid State Ionics, 177 (2006), 2721-2725). ４－ｘ Ge １－ｘ P ｘ S ４ Thio-LISICON Region II crystal structure, Li ４－ｘ Ge １－ｘ P ｘ S ４This indicates that the thio-LISICON region II type has a similar crystal structure.

[0055] In X-ray diffraction measurement using CuKα radiation, Li ３ P.S. ４ Diffraction peaks of the crystal structure appear, for example, at 2θ=17.5°, 18.3°, 26.1°, 27.3°, and 30.0°. ４ P ２ S ６ Diffraction peaks of the crystal structure appear, for example, at 2θ=16.9°, 27.1°, and 32.5°. ７ P.S. ６ Diffraction peaks of the crystal structure appear, for example, at 2θ=15.3°, 25.2°, 29.6°, and 31.0°. ７ P ３ S １１ Diffraction peaks of the crystal structure appear, for example, at 2θ=17.8°, 18.5°, 19.7°, 21.8°, 23.7°, 25.9°, 29.6°, and 30.0°, and Li ４－ｘ Ge １－ｘ P ｘ S ４ The diffraction peaks of the thio-LISICON Region II crystal structure appear, for example, at 2θ=20.1°, 23.9°, and 29.5°, and Li ４－ｘ Ge １－ｘ P ｘ S ４ Diffraction peaks of a crystal structure similar to that of thio-LISICON Region II type appear, for example, at 2θ=20.2° and 23.6°. Note that these peak positions may vary within a range of ±0.5°.

[0056] The crystal structure of the crystalline sulfide solid electrolyte also includes an argyrodite-type crystal structure. ７ P.S. ６ Crystal structure; Li ７ P.S. ６ The structural skeleton of the composition formula Li ７－ｘ P １－ｙ Si ｙ S６ and Li ７＋ｘ P １－ｙ Si ｙ S ６ (x is -0.6 to 0.6, y is 0.1 to 0.6); Li ７－ｘ－２ｙ P.S. ６－ｘ－ｙ Cl ｘ (0.8≦x≦1.7, 0<y≦−0.25x+0.5); Li ７－ｘ P.S. ６－ｘ Ha ｘ (Ha is Cl or Br, and x is preferably 0.2 to 1.8).

[0057] Among the above crystal structures, the crystal structure of the crystalline sulfide solid electrolyte is Li ３ P.S. ４ The crystal structure, the thiolicon region II crystal structure, and the argyrodite crystal structure are preferred.

[0058] The shape of the crystalline sulfide solid electrolyte is not particularly limited, but may be, for example, particulate. The average particle diameter (D ５０ ) is the average particle size (D ５０ ) and the ranges of 0.01 μm to 500 μm and 0.1 μm to 200 μm can be exemplified.

[0059] [Solid Electrolyte] Production Example 1 (Preparation of Solid Electrolyte A) 0.4398 g of lithium sulfide, 0.7084 g of diphosphorus pentasulfide, 0.2133 g of lithium iodide, 0.1384 g of lithium bromide, and 10 zirconia balls having a diameter of 10 mm were placed in a 45 mL zirconia pot and sealed. Using a planetary ball mill (manufactured by Fritsch, model number P-7), the mixture was mixed (mechanical milling) at a rotation speed of 370 rpm for 40 hours to obtain a powder. The obtained powder was heated at 195 ° C. for 3 hours to obtain a solid electrolyte A.

[0060] Production Example 2 (Preparation of Solid Electrolyte B) 15.3 g of lithium sulfide and 24.7 g of diphosphorus pentasulfide were placed in a 1 L reactor equipped with a stirring blade under a nitrogen atmosphere. After the stirring blade was turned on, 400 mL of tetrahydrofuran cooled to -20°C was added to the vessel. After allowing the temperature to rise naturally to room temperature and stirring for 72 hours, the resulting reaction solution slurry was placed in a glass filter (pore size: 40 to 100 μm) to obtain a solid content. The solid content was dried at 90°C to obtain Li ３ P.S. ４ The obtained Li powder (purity: 90% by mass) was placed in a Schlenk flask (volume: 100 mL) equipped with a stirrer under a nitrogen atmosphere. ３ P.S. ４ 1.70 g of powder, 0.19 g of lithium bromide, and 0.28 g of lithium iodide were added. After rotating the stirrer, 20 mL of the complexing agent tetramethylethylenediamine (TMEDA) was added and stirred for 12 hours. The obtained electrolyte precursor content was dried under vacuum at room temperature to obtain a powdered electrolyte precursor. The obtained electrolyte precursor was heated under vacuum at 120°C for 2 hours, and further heated under vacuum at 140°C for 2 hours to obtain solid electrolyte B.

[0061] Production Example 3 (Preparation of Solid Electrolyte C) Lithium sulfide (Li ２ S), diphosphorus pentasulfide (P ２ S ５ ), lithium bromide (LiBr) and lithium chloride (LiCl) in a molar ratio of Li ２ S:P ２ S ５The raw materials were roughly mixed to obtain a ratio of 47.5:12.5:15.0:25.0 of LiBr:LiCl. The raw material mixture was dispersed in a mixed solvent of dehydrated toluene and 2% by mass of dehydrated isobutyronitrile relative to the raw material mixture to obtain a slurry of approximately 10% by mass. A bead mill was operated at a peripheral speed of 12 m / s and a flow rate of 500 mL / min, and the slurry was introduced into the mill and circulated for 1 hour to obtain a mixture. After removing the solvent from the obtained mixture, the mixture was heated at 400 to 430 °C for 2 hours in an electric furnace. The mixture was then slowly cooled to obtain a raw material sulfide solid electrolyte. The raw material sulfide solid electrolyte was dispersed in dehydrated toluene under a nitrogen atmosphere and placed in a zirconia pot of a planetary ball mill (manufactured by Fritsch: model number P-7) together with 0.3 mm diameter zirconia balls, and the pot was filled with an inert atmosphere. The planetary ball mill was rotated at 150 rpm for 2 hours to obtain a slurry containing a finely divided sulfide solid electrolyte. The slurry was transferred to a nitrogen-substituted Schlenk flask, dried at room temperature for 1 hour using a vacuum pump, and then heated to 80°C to 100°C to further remove the solvent contained in the finely divided sulfide solid electrolyte (drying under reduced pressure), thereby obtaining solid electrolyte C.

[0062] [Positive electrode composite precursor] Example 1 (1) Preparation of composite powder Activated carbon (MSC-30SSS, manufactured by Kansai Thermal Chemical Industry Co., Ltd.) and sulfur were placed in a glass bottle in a mass ratio of 3:7, and the bottle was sealed in an SUS tubular container. The mixture was heated in an electric furnace at 150°C for 6 hours and then at 300°C for 2.75 hours to obtain a powder of a composite of activated carbon and sulfur (S-C composite).

[0063] (2) Preparation of a cathode composite precursor The composite powder obtained in (1) above and diphosphorus pentasulfide (manufactured by Italmatch, melting point 286 to 290°C) were placed in a Tammann tube with an inner diameter of 12 mm in a mass ratio of 0.7143:0.2857, and the resulting mixture was sealed in an SUS tube. The mixture was heated in an electric furnace at 350°C for 6 hours to obtain a cathode composite precursor.

[0064] Example 2 A positive electrode composite precursor was obtained in the same manner as in Example 1, except that the powder of the composite obtained in Example 1(1) above and diphosphorus pentasulfide (manufactured by Italmatch, melting point 286 to 290°C) were placed in a Tammann tube having an inner diameter of 12 mm in a mass ratio of 0.8333:0.1667.

[0065] Example 3 Activated carbon (MSC-30SSS, manufactured by Kansai Thermal Chemical Industry Co., Ltd.), sulfur, and diphosphorus pentasulfide (Italmatch, melting point 286 to 290°C) were placed in a mass ratio of 0.2143:0.5000:0.2857 in a Tammann tube having an inner diameter of 12 mm, and the tube was sealed in an SUS tubular container. The mixture was heated in an electric furnace at 350°C for 6 hours to obtain a positive electrode composite precursor.

[0066] Example 4 A positive electrode composite precursor was obtained in the same manner as in Example 1, except that the powder of the composite obtained in Example 1(1) above, diphosphorus pentasulfide (manufactured by Italmatch, melting point 286 to 290°C), and sulfur were placed in a Tammann tube having an inner diameter of 12 mm in a mass ratio of 0.7143:0.2143:0.0714.

[0067] Example 5 A positive electrode composite precursor was obtained in the same manner as in Example 1, except that the powder of the composite obtained in Example 1(1) above, diphosphorus pentasulfide (manufactured by Italmatch, melting point 286 to 290°C), and sulfur were placed in a Tammann tube having an inner diameter of 12 mm in a mass ratio of 0.6667:0.2666:0.0667.

[0068] Example 6 A positive electrode composite precursor was obtained in the same manner as in Example 1, except that activated carbon (manufactured by Kansai Thermochemical Co., Ltd., MSC-30SSS) was replaced with activated carbon (manufactured by Kansai Thermochemical Co., Ltd., MSC-30).

[0069] Comparative Example 1 The composite powder obtained in Example 1(1) above was used as a positive electrode mixture precursor.

[0070] Comparative Example 2 The powder of the composite obtained in Example 1 (1) above and diphosphorus pentasulfide (manufactured by Italmatch, melting point 286 to 290°C) were charged into an agate mortar in a mass ratio of 0.7143:0.2857 and mixed for 5 minutes to obtain a positive electrode composite precursor.

[0071] Comparative Example 3 A positive electrode composite precursor was obtained in the same manner as in Comparative Example 2, except that the powder of the composite obtained in Example 1 (1) above and diphosphorus pentasulfide (manufactured by Italmatch, melting point 286 to 290°C) were charged into an agate mortar in a mass ratio of 0.8333:0.1667.

[0072] [Evaluation] The following evaluations were performed on the positive electrode composite precursors prepared in the Examples and Comparative Examples. (1) X-ray Photoelectron Spectroscopy (XPS) Measurement (a) XPS Measurement In a glove box controlled to an Ar atmosphere with a dew point of -60°C or less, double-sided carbon tape was attached to a metal substrate, and a powder sample was pressed onto the tape with a spatula. The surface of the spatula used was cleaned with an organic solvent such as acetone. A metal perforated mask (holes 5 mm in diameter) was placed on the tape with the powder sample fixed, and the mask was fixed with screws to prepare a measurement sample. To prevent the sample from being exposed to the atmosphere, a transfer vessel was used to introduce the sample into the XPS apparatus, and measurements were performed. Detailed measurement conditions for XPS are shown below.

[0073] XPS apparatus: VersaProbe II (ULVAC-PHI, Inc.) X-ray source: Monochromated AlKα radiation (1486.6 eV) measured at a high power of 100 W X-ray diameter: 100 μm (measured by sweeping over a range of 200 μm x 1200 μm) Pass energy: 23.5 eV (C1s, S2p, P2p) 46.95 eV (O1s, Li1s, Br3d, I3d5 / 2, Cl2p) Step energy: 0.1 eV (C1s, S2p, P2p) 0.2 eV (O1s, Li1s, Br3d, I3d5 / 2, Cl2p) Photoelectron detection angle: 45°

[0074] XPS measurements were performed on three samples: the surface (outermost surface) of the sample, and the interiors A and B of two types of samples with the surface layer cut off. The sample surfaces were not subjected to the surface treatment described below. The samples were placed in an ultra-high vacuum (1.0 × 10 －７ The measurements were taken immediately after the sample was introduced into a vacuum (less than 100 Pa). Sample interiors A and B were measured after surface treatment using the following sputter ion gun. Sample interior A: Argon gas cluster ion beam (Ar-GCIB): 10 kV, 30 nA, 2 mm x 2 mm, 5 minutes Sample interior B: Ar monomer ion: 1 kV, 7 mA, 2 mm x 2 mm, 60 minutes

[0075] (b) Relative intensity of the sample surface in the P2p spectrum. The analysis software used was MultiPak manufactured by ULVAC-PHI. ８The peak position of the P2p orbital was set to 164.1 eV for charge correction. The background of the spectrum derived from the P2p orbital was subtracted by the Shirley method, and the cps values ​​(signal intensity: I) were extracted for three peaks: a peak with a binding energy of approximately 135.4 eV (Peak A), a peak with a binding energy of approximately 134.25 eV (Peak B), and a peak with a binding energy of approximately 133.0 eV (Peak C). The signal intensity ratio (I Ａ / I Ｂ and I Ｃ / I Ｂ ) was calculated. Note that "near" means that the position of the binding energy may vary slightly depending on the measurement device, etc. For example, Position A refers to a peak appearing in the range of 135.0 eV to 136.5 eV, Position B refers to a peak appearing in the range of 133.5 eV to less than 135.0 eV, and Position C refers to a peak appearing in the range of 132.0 eV to less than 133.5 eV. Furthermore, if no clear peak appears at each position, Position A is designated as 135.4 eV, Position B as 134.25 eV, and Position C as 133.0 eV. The P2p relative intensity on the sample surface is the value at one point near the center of the measurement area (diameter 5 mm). It was confirmed that the spectra of each element were nearly identical at a total of three points in the measurement area: near the center and two points approximately 500 μm away from the center. The P2p spectra of Examples 1 to 6 and Comparative Example 2 are shown in Figures 1 to 7. In the figure, A indicates position A where the binding energy is around 135.4 eV, B indicates position B where the binding energy is around 134.25 eV, and C indicates position C where the binding energy is around 133.0 eV.

[0076] (c) Elemental ratio C / P of carbon and phosphorus elements Analysis software used was MultiPak manufactured by ULVAC-PHI. The background was subtracted from each spectrum by the Shirley method, and the elemental ratio C / P was calculated from the obtained area intensity using the relative sensitivity coefficient. The carbon element peak has a peak top near 278-298 eV, and the phosphorus element peak has a peak top near 123-143 eV. The elemental ratio C / P on the sample surface was taken as the average value of three arbitrary points within the measurement area (diameter 5 mm). The elemental ratio C / P of the sample interiors A and B was taken as the value of one arbitrary point within the measurement area. The C / P change rate R between the surface and interior AＡ , and the C / P change rate R between the surface and the interior B Ｂ was calculated using the following formula: Ａ = (element ratio C / P in sample interior A) / (element ratio C / P on surface) R Ｂ = (element ratio C / P of sample interior B) / (element ratio C / P of surface)

[0077] (d) The area of ​​the PSx peak on the sample surface in the S2p spectrum and S ８ The area ratio of the peak (S ８ The analysis software used was MultiPak manufactured by ULVAC-PHI. The sulfur element peak has a peak top in the range of 155 to 175 eV. The S in the spectrum derived from the S2p orbital ８ Charge correction was performed with the peak position derived from the PS as 164.1 eV. The Shirley method was used for background subtraction. ４ -like (hereinafter referred to as PSx) and S ８ The abundance ratio (area ratio) of each was determined by waveform separation of the S2p spectrum. ８ , 2p3 / 2), 165.2 to 165.4 eV (S ８ , S2p1 / 2), 162.40-162.60 eV (PSx, S2p3 / 2), 163.6-163.8 eV (PSx, S2p1 / 2), with a half-width of 1.1 or more and less than 1.3 eV. ８ The peak area ratio is the value at one point near the center of the measurement area (diameter 5 mm). It was confirmed that the state spectra of each element at three points on the sample surface, one near the center and two points about 500 μm away from the center, were almost the same. The S2p spectra of Examples 1 and 2 and Comparative Example 2 are shown in Figures 8 to 10. The evaluation results of the XPS measurements are also shown in Table 1. The "P ２ S ５ The "state of" is the S-C complex and P ２ S ５ This shows the state when mixed.

[0078]

[0079] As shown in Table 1, in the example, the signal intensity ratios I Ａ / I Ｂ and I Ｃ / I Ｂ At least one of these was greater than 0.8. ２ S ５ The peak due to P appears at position B. In Comparative Example 2, peak B clearly appears at position B, and ２ S ５ It was suggested that P exists in its original chemical state. On the other hand, in the examples, it was confirmed that peaks A and C appear instead of peak B. Peaks A and C are P ２ S ５ In the example, the presence of a modified form of P was mixed in a molten state with an S-C composite. ２ S ５ It is believed that P exists in the positive electrode composite precursor in a chemical state different from the original state. ２ S ５ It is presumed that the peak contains elements such as O and C derived from activated carbon in addition to P and S in the activated carbon. Carbon materials such as activated carbon generally contain C and O. Peak A is the peak of molten P. ２ S ５ It is thought that this represents a component generated by a reaction between P and a part of the activated carbon inside or on the surface of the activated carbon. ２ S ５ Since the difference in bond energy between ２ S ５ It is not, but does not contain O or C, etc. ２ It is presumed that the component is Sx (5<x). ２ S ５ It is thought that the peak C is due to the influence of the component of peak A produced during melting of activated carbon, and the component produced inside or on the surface of activated carbon by reacting with sulfur in the molten state. ２ S ５ When comparing the results of Example 1 and Example 2, which have different blending amounts of P, it can be seen that peak A has the same signal intensity, while peak C has a signal intensity of P ２ S５ It was confirmed that the signal intensity was high in Example 1, where the amount of molten P ２ S ５ It is thought that the change in the S-C complex is due to the reaction inside or on the surface of the activated carbon, which produces the component indicated by peak A first, and the remaining part changes to the component indicated by peak C, also inside or near the surface of the activated carbon, and both components coat the S-C complex. ２ S ５ This is thought to indicate that the S—C composite was coated with the SiO2 and a strong interface was formed.

[0080] In the examples, the carbon to phosphorus element ratio C / P on the surface of the positive electrode composite precursor was small. ２ S ５ is contacted with the SC complex, ２ S ５ and / or P ２ S ５ This is thought to be because the surface of the S—C composite was covered with the modified product, resulting in a relative increase in phosphorus and a decrease in carbon detected on the surface.

[0081] In addition, in the examples, the change rate of C / P in the interior A and the interior B relative to the C / P on the surface of the positive electrode composite precursor was large. This is also due to the same reason as above, that the S-C composite is P ２ S ５ and / or P ２ S ５ In the examples where the modified material of the present invention is coated, the proportion of each component differs between the surface and the interior very close to the surface, which is thought to have promoted uneven distribution of each component in the depth direction.

[0082] In the examples, the S of the PSx peak ８ It was confirmed that the area ratio of the surface to the peak increased. ２ S ５ and / or P ２ S ５ In the example where the cathode composite precursor is coated with the modified product of P, the amount of the S—C composite exposed on the surface of the cathode composite precursor is relatively reduced. ２ S ５ and / or P ２S ５ The PSx peak, which is a peak derived from a denatured product of ８ This is thought to be because the peak is detected relatively stronger than the peak of

[0083] (2) Calculation of the occupancy rate of the main component by energy dispersive X-ray spectroscopy (SEM-EDS analysis) of scanning electron microscope images (a) Preparation of positive electrode composite precursor pellets 100 mg of the positive electrode composite precursor powder was placed in a Macol cylinder having a diameter of 10 mm and pressure-molded. The molded body was then removed from the cylinder to obtain positive electrode composite precursor pellets.

[0084] (b) SEM-EDS Analysis The cathode composite precursor pellet was split vertically, and the exposed surface was subjected to ion milling (Hitachi High-Tech Corporation, IM4000) to expose the cross section of the cathode composite precursor pellet. SEM-EDS elemental mapping measurement was performed on the obtained cross section using an SEM (Hitachi High-Tech Corporation, SU8220) and an EDS (Bruker, QUANTAX FlatQUAD), and secondary electron images and EDS images of each component (sulfur, carbon, phosphorus, etc.) were obtained from 10 fields of view. The observation magnification was 5000x, the acceleration voltage was 10 kV, and the scan area was 1024 x 768. For EDS mapping, a smoothing process was performed using the software of the EDS device, and the obtained image was used. In addition, when performing SEM-EDS elemental mapping measurement, the area cross-sectionally processed by ion milling was divided into two equal parts, top and bottom, and each of these two equal parts was divided into five equal parts left and right. The central portion of each of the 10 divided regions was subjected to SEM-EDS elemental mapping at a magnification of 5000 times.

[0085] (c) Calculation of Principal Component Occupancy Rates. The images obtained using the above procedure were processed using Python (3) OpenCV (4.5.1). For each field of view, the EDS intensity information for carbon, phosphorus, and sulfur for each pixel was arrayed and converted to an HSV color space file format. The HSV file was smoothed using a median filter. The smoothed image was segmented using simple linear iterative clustering, and the average HSV intensity value for each segment was obtained. For each segment, the average HSV intensity value of 25 or more was defined as a principal component, and the proportion of this value relative to the field of view was calculated as the principal component occupation rate. The results are shown in Table 2. Figure 11(a) shows the image data obtained by overlaying the EDS mappings of C, P, and S in Example 1, and Figure 11(b) shows the image obtained by image processing of (a). Fig. 12(a) is image data obtained by superimposing EDS mappings of C, P, and S in Example 2, and Fig. 12(b) is an image obtained by image processing of (a). Fig. 13(a) is image data obtained by superimposing EDS mappings of C, P, and S in Comparative Example 2, and Fig. 13(b) is an image obtained by image processing of (a). Fig. 14(a) is image data obtained by superimposing EDS mappings of C, P, and S in Comparative Example 3, and Fig. 14(b) is an image obtained by image processing of (a). The white areas in each figure (b) indicate the main component regions.

[0086]

[0087] As shown in Table 2, it can be confirmed that the occupancy rate of the main component is high in the examples. This is because the coating allows the S-C composite and P ２ S ５ and / or P ２ S ５ This is thought to be because the modified forms of the hydroxybenzoates and the modified forms of the hydroxybenzoates came to exist in close proximity to each other.

[0088] (3) BET Specific Surface Area: Measurement was performed using a specific surface area / pore distribution measuring device (Autosorb-3) manufactured by Quantacrome Co., Ltd. The results are shown in Table 3.

[0089]

[0090] From Table 3, it can be seen that the specific surface area of ​​the precursor obtained in the examples is small.２ S ５ By mixing the above into the SC composite, the surface of the SC composite is treated with P ２ S ５ and / or P ２ S ５ This is thought to be because the modified product was coated.

[0091] (4) Crystallinity Evaluation by X-ray Diffraction Measurement (XRD) The positive electrode composite precursor powder was filled into a groove with a diameter of 20 mm and a depth of 0.2 mm and leveled with glass to prepare a sample. This sample was sealed with a Kapton film for XRD and measured without being exposed to air. The XRD measurement was performed using a powder X-ray diffraction measurement device D2 PHASER manufactured by BRUKER Co., Ltd. under the following measurement conditions.

[0092] Tube voltage: 30 kV Tube current: 10 mA X-ray wavelength: Cu-Kα ray (1.5418 Å) Optical system: Concentration method Slit configuration: Soller slit 4° (both incident and receiving sides), divergence slit 1 mm, Kβ filter (Ni plate 0.5%), air scatter screen 3 mm) Detector: Semiconductor detector Measurement range: 2θ = 10-60 deg Step width, scan speed: 0.05 deg, 0.05 deg / sec

[0093] The presence or absence of a crystalline peak in the obtained spectrum confirmed the crystallinity of the sample. ２ S ５ Since the crystal peaks are at positions such as "2θ = 10.81°, 12.12°, 14.90°, 16.07°, 21.68°, 25.67°, and 30.33°," it was confirmed whether the crystal peaks were maintained at these positions in the positive electrode composite precursor state. The results are shown in Table 4. X-ray diffraction charts of Examples 1 and 2 and Comparative Examples 2 and 3 are shown in Figures 15 to 18.

[0094]

[0095] From Table 4, in the example, P ２ S ５ It can be seen that no diffraction peaks originating from crystals of P are observed. ２ S ５It is expected that the crystallinity of disappears upon melting, and the amorphous phase remains around the SC composite, forming a strong interface.

[0096] (5) Solid ３１ Area ratio of each phosphorus component by P-NMR measurement Measurement was performed using the following apparatus under the following conditions: Apparatus: ECZL400G (manufactured by JEOL Ltd.) Magnetic field strength: 400 MHz Detector: 3.2 mm auto MAS probe Solid-state NMR sample tube diameter: 3.2 mm Observation nucleus: ３１ P Observation frequency: 161.835 MHz Measurement temperature: room temperature Pulse sequence: single pulse 90° pulse length: 3.4 μs Flip angle: 45° Number of FID acquisition points: 1,024 points Waiting time after FID measurement until next pulse application: 1,500 s MAS (magic angle spinning) rotation speed: 14 kHz Number of accumulations: 64 Measurement range: 400 ppm to -300 ppm External standard: NH ４ H ２ P.O. ４ (chemical shift 1.00 ppm)

[0097] solid ３１ The data processing conditions for the P-NMR measurements were an exponential function as the window function, and a value within the range in which the half-width of the peak did not change significantly was used as the line broadening value, depending on the signal-to-noise ratio of each sample. The actual values ​​of the line broadening values ​​are described in the Examples and Comparative Examples. Backward linear prediction was not used.

[0098] When peak separation is required, the obtained solid ３１ The P-NMR spectrum was analyzed to determine the separated peaks. ３１ From each NMR peak (experimental value) on the P-NMR spectrum, peak separation was performed using the nonlinear least squares method and a Gaussian function to calculate the separated peaks, and the calculated values ​​of the NMR peaks and the residual sum of squares R2 were calculated. ３１The assignment of each peak obtained by waveform separation of the P-NMR spectrum was performed with reference to the following documents 1 to 3. Document 1: Christian Dietrich et al. J. Mater. Chem. A, 2017, 5, 18111-18119. Document 2: Japanese Patent No. 6719037. Document 3: Japanese Patent No. 7297911.

[0099] For example, as disclosed in Reference 1, the peak at around 125 ppm obtained by waveform separation is PS ３ － As disclosed in Reference 2, the peak at around 106 ppm was assigned to P ２ S ６ ４－ (amorphous), the peak around 91 ppm is P ２ S ７ ４－ (amorphous), the peak around 84 ppm is PS ４ ３－ As disclosed in Reference 3, the peak around 50 to 60 ppm obtained by waveform separation was attributed to P ２ S ５ In addition, P in this attribution ２ S ５ Generally, the main component of diphosphorus pentasulfide is P ４ S １０ Skeleton and P ４ S ９ It is considered to be the total value of the skeleton, etc. As peaks that cannot be assigned in References 1 to 3, a peak of unknown assignment was observed at −30 ppm in Example 1 and at 86 ppm in Comparative Example 2.

[0100] solid ３１ The composition calculation of each component obtained by waveform separation of the P-NMR spectrum was carried out by using the area value of the separated peak as a percentage to calculate the proportion of each component shown below. Spinning sideband peaks were not used in calculating the composition of each component. The area ratio (%) of each peak to the total area of ​​the seven peaks shown in Table 5 was calculated. The results are shown in Table 5. ３１ The results of waveform separation of the P-NMR spectrum are shown in Figures 19 (line broadening value 200 Hz) and 20 (line broadening value 100 Hz).

[0101]

[0102] From Table 5 and Figures 19 and 20, it was confirmed that the peak components in the range of 50 to 60 ppm were less in the Examples than in the Comparative Examples, and conversely, the peak components around 106.0 ppm, 91 ppm, and 84 ppm increased. ２ S ５ , P ２ S ６ ４－ , P ２ S ７ ４－ , P.S. ４ ２－ In the examples, the melted P ２ S ５ The component reacts partially with sulfur in the S-C complex, for example, inside or near the surface of the activated carbon, to form P ２ S ６ ４－ , P ２ S ７ ４－ , P.S. ４ ２－ This is because the P mixed in the molten state ２ S ５ It is considered that this indicates that the molten P coats the SC composite in a partially denatured state, forming a strong interface. ２ S ５ coated the S-C composite and formed a strong interface, resulting in P ２ S ５ When the ratio of P becomes equal to or less than a certain value (for example, 60%), ２ S ６ ４－ , P ２ S ７ ４－ and P.S. ４ ２－ The total value of the percentages is equal to or greater than a certain value (for example, 30%).

[0103] [Cathode Composite] Example 7 0.6300 g of the cathode composite precursor of Example 1 and 0.2700 g of solid electrolyte A were placed in a 45 mL zirconia pot together with 34 g of zirconia balls with a diameter of 2 mm, and the pot was sealed. Mixing was carried out at room temperature and a rotation speed of 600 rpm for 1 hour using a tumbling mill ("Small Ball Mill Stand", manufactured by Asahi Rika Seisakusho, Model AV-1) to obtain a powder of the cathode composite.

[0104] Example 8 A powder of a positive electrode mixture was obtained in the same manner as in Example 7, except that 0.5400 g of the positive electrode mixture precursor of Example 2 and 0.3600 g of solid electrolyte A were used.

[0105] Example 9 A powder of a positive electrode mixture was obtained in the same manner as in Example 7, except that 0.6300 g of the positive electrode mixture precursor of Example 1 and 0.2700 g of solid electrolyte B were used.

[0106] Example 10 A powder of a positive electrode mixture was obtained in the same manner as in Example 7, except that 0.6300 g of the positive electrode mixture precursor of Example 1 and 0.2700 g of solid electrolyte C were used.

[0107] Example 11 A powder of a positive electrode mixture was obtained in the same manner as in Example 7, except that 0.6300 g of the positive electrode mixture precursor of Example 3 and 0.2700 g of solid electrolyte C were used.

[0108] Example 12 A powder of a positive electrode mixture was obtained in the same manner as in Example 7, except that 0.6300 g of the positive electrode mixture precursor of Example 4 and 0.2700 g of solid electrolyte C were used.

[0109] Example 13 A powder of a positive electrode mixture was obtained in the same manner as in Example 7, except that 0.6750 g of the positive electrode mixture precursor of Example 5 and 0.2250 g of solid electrolyte C were used.

[0110] Example 14 A powder of a positive electrode mixture was obtained in the same manner as in Example 7, except that 0.6300 g of the positive electrode mixture precursor of Example 6 and 0.2700 g of solid electrolyte C were used.

[0111] Comparative Example 4 0.4500 g of the composite powder obtained in the same manner as in Example 1(1) and 0.4500 g of solid electrolyte A were mixed in a tumbling mill in the same manner as in Example 7 to obtain a powder of a positive electrode mixture.

[0112] Comparative Example 5 0.4500 g of a powder of a composite obtained in the same manner as in Example 1(1), 0.1800 g of diphosphorus pentasulfide, and 0.2700 g of solid electrolyte A were mixed in a tumbling mill in the same manner as in Example 7 so that the mass ratio of activated carbon, sulfur, and diphosphorus pentasulfide was the same as in Example 7, thereby obtaining a powder of a positive electrode composite.

[0113] Comparative Example 6 0.4500 g of a powder of a composite obtained in the same manner as in Example 1(1), 0.0900 g of diphosphorus pentasulfide, and 0.3600 g of solid electrolyte A were mixed in a tumbling mill in the same manner as in Example 7 so that the mass ratio of activated carbon, sulfur, and diphosphorus pentasulfide was the same as in Example 8, to obtain a powder of a positive electrode composite.

[0114] All-solid-state lithium-ion batteries were fabricated using the positive electrode composites fabricated in the above Examples and Comparative Examples, as described below, and the battery characteristics (charge and discharge characteristics) were evaluated. - Fabrication of negative electrode composite Lithium titanate ("LT-112" manufactured by Ishihara Sangyo Kaisha), a conductive additive ("Li-100" manufactured by Denka Co., Ltd., powdered acetylene black), and solid electrolyte C were mixed in a mortar in a mass ratio of 60:5:35 for 5 minutes to obtain a negative electrode composite (also referred to as "LTO (lithium titanate) negative electrode composite").

[0115] - Preparation of Lithium-ion Battery 100 mg of solid electrolyte A was placed in a 10 mm diameter Macol cylinder and pressure molded to form a solid electrolyte layer (layer of solid electrolyte A). Next, 10 mg of positive electrode composite powder was placed on one pressure surface of the solid electrolyte layer and pressure molded again. Next, 166 mg of LTO negative electrode composite was placed on the other pressure surface of the solid electrolyte layer (the pressure surface opposite the positive electrode) and pressure was applied. A Li foil with a diameter of 9 mm and a thickness of 0.1 mm was placed on top of it and pressure was applied again to prepare a lithium-ion battery.

[0116] Charge / Discharge Test A constant current charge / discharge test was performed on the lithium ion batteries using the positive electrode composites of each Example and Comparative Example. The voltage range for the constant current charge / discharge test was set to -0.4 to 1.3 V, and the current value was set as shown in Table 6 at a C rate determined based on the theoretical capacity of sulfur of 1672 mAh / g. The test was performed. For charging, CC-CV charging was performed, in which constant voltage charging was performed with a termination condition of 0.02 C after constant current charging, and for discharging, constant current discharge (CC discharge) was performed. The results are shown in Table 7.

[0117]

[0118]

[0119] It was confirmed that the Examples had higher discharge capacities at both low and high rates than the Comparative Examples. ２ S ５ The improvement in charge-discharge characteristics was confirmed in the examples in which a cathode composite precursor was prepared by melting an ion conductor (a cathode composite precursor of the present invention). It is believed that the excellent charge-discharge characteristics were obtained in the examples by using the cathode composite precursor of the present invention, which has a strong interface and a good ion conduction path.

[0120] Example 15 0.6300 g of the positive electrode composite precursor of Example 1 and 0.2700 g of solid electrolyte A were placed in a 45 mL zirconia pot together with ten zirconia balls having a diameter of 10 mm and sealed. Using a planetary ball mill (manufactured by Fritsch, model number P-7), the mixture was mixed (mechanical milling) at room temperature and a rotation speed of 370 rpm for 20 hours to obtain a positive electrode composite powder. The results of evaluation in the same manner as in Example 7 are shown in Table 8.

[0121] Example 16 A powder of a positive electrode mixture was obtained in the same manner as in Example 15, except that 0.5400 g of the positive electrode mixture precursor of Example 2 and 0.3600 g of solid electrolyte A were used. The evaluation results are shown in Table 8.

[0122] Comparative Example 7 0.4500 g of the composite powder obtained in the same manner as in Example 1(1) and 0.4500 g of solid electrolyte A were mixed in the same manner as in Example 15 to obtain a powder of a positive electrode mixture. The evaluation results are shown in Table 8.

[0123] Comparative Example 8 A powder of a positive electrode mixture was obtained by mixing 0.4500 g of a powder of a composite obtained in the same manner as in Example 1(1), 0.1800 g of diphosphorus pentasulfide, and 0.2700 g of solid electrolyte A in the same manner as in Example 15 so that the mass ratio of activated carbon, sulfur, and diphosphorus pentasulfide was the same as in Example 15. The evaluation results are shown in Table 8.

[0124] Comparative Example 9 A powder of a positive electrode mixture was obtained in the same manner as in Example 15 by mixing 0.4500 g of a powder of a composite obtained in the same manner as in Example 1(1), 0.0900 g of diphosphorus pentasulfide, and 0.3600 g of solid electrolyte A so that the mass ratio of activated carbon, sulfur, and diphosphorus pentasulfide was the same as in Example 16. The evaluation results are shown in Table 8.

[0125]

[0126] It can be seen that the Examples have higher capacities at both low and high rates compared to the Comparative Examples. Comparative Example 7 has a low high-rate capacity, and Comparative Examples 8 and 9 have low low-rate capacities. On the other hand, the Examples have high capacities at both rates.

[0127] Example 17 (1) First Mixing Step 1.000 g of the positive electrode composite precursor of Example 1 was placed in a 45 mL zirconia pot together with ten zirconia balls having a diameter of 10 mm, and the pot was sealed. The mixture was mixed and pulverized at room temperature and a rotation speed of 370 rpm for 20 hours using a planetary ball mill (manufactured by Fritsch GmbH, model number P-7).

[0128] (2) Second Mixing Step: 0.6300 g of the processed product (first mixture) from (1) above and 0.2700 g of solid electrolyte A were placed in a 45 mL zirconia pot along with 34 g of zirconia balls with a diameter of 2 mm, and the pot was sealed. Using a tumbling mill ("Small Ball Mill Stand," manufactured by Asahi Rika Seisakusho, model number AV-1), the mixture was mixed at room temperature at a rotation speed of 600 rpm for 1 hour to obtain a powder of a positive electrode composite. The results of evaluation in the same manner as in Example 7 are shown in Table 9.

[0129] Comparative Example 10 (1) First Mixing Step The composite powder obtained in the same manner as in Example 1 (1) and diphosphorus pentasulfide were placed in a 45 mL zirconia pot together with ten zirconia balls having a diameter of 10 mm, so as to have the same mass ratio as the processed product obtained in Example 17 (1), and the pot was sealed. The mixture was mixed and pulverized at room temperature and a rotation speed of 370 rpm for 20 hours using a planetary ball mill (manufactured by Fritsch, model number P-7).

[0130] (2) Second Mixing Step: 0.6300 g of the processed product (1) (first mixture) and 0.2700 g of solid electrolyte A were mixed in the same manner as in Example 17 to obtain a powder of a positive electrode mixture. The evaluation results are shown in Table 9.

[0131]

[0132] From Table 9, it can be seen that the capacity of the Example is higher than that of the Comparative Example at all rates.

[0133] Example 18 (1) Preparation of Positive Electrode Composite Precursor A positive electrode composite precursor was prepared in the same manner as in Example 1(2), except that a powder of the composite prepared in the same manner as in Example 1(1) and diphosphorus pentasulfide (manufactured by Italmatch, melting point 286 to 290°C) were placed in a Tammann tube having an inner diameter of 12 mm in a mass ratio of 5:5.

[0134] (2) Preparation of Positive Electrode Composite Powder 0.9000 g of the positive electrode composite precursor obtained in (1) above was placed in a 45 mL zirconia pot together with 10 zirconia balls having a diameter of 10 mm and sealed. Using a planetary ball mill (manufactured by Fritsch, model number P-7), the mixture was mixed at room temperature and a rotation speed of 370 rpm for 20 hours to obtain a positive electrode composite powder. The results of the evaluation performed in the same manner as in Example 7 are shown in Table 10.

[0135] Comparative Example 11 0.4500 g of composite powder obtained in the same manner as in Example 1 (1) and 0.4500 g of diphosphorus pentasulfide were placed in a 45 mL zirconia pot together with ten zirconia balls having a diameter of 10 mm and sealed. Using a planetary ball mill (manufactured by Fritsch, model number P-7), the mixture was mixed at room temperature and a rotation speed of 370 rpm for 20 hours to obtain a powder of a positive electrode composite. The evaluation results are shown in Table 10.

[0136]

[0137] From Table 10, it can be seen that the Examples have higher capacities than the Comparative Examples at all rates.

[0138] The cathode composite precursor of the present invention and the cathode composite precursor produced by the present invention can be suitably used, for example, as a cathode composite and a constituent material of a cathode of an all-solid-state lithium-ion battery. The cathode composite of the present invention is suitable as a constituent material of a lithium-ion battery. Furthermore, a lithium-ion battery containing the cathode composite produced by the present invention can be suitably used, for example, as a battery used in information-related devices and communication devices such as personal computers, video cameras, and mobile phones, and vehicles such as electric vehicles.

[0139] Although several embodiments and / or examples of the present invention have been described in detail above, those skilled in the art will readily be able to make numerous modifications to these exemplary embodiments and / or examples without substantially departing from the novel teachings and advantages of the present invention. Accordingly, these numerous modifications are within the scope of the present invention. The contents of all references cited in this specification and the applications from which this application claims priority under the Paris Convention are incorporated by reference in their entirety. In this specification, "x to y" represents a numerical range of "greater than or equal to x and less than or equal to y." The upper and lower limits of numerical ranges can be arbitrarily combined. Furthermore, two or more of the individual embodiments of the present invention that are not mutually exclusive can be combined, and an embodiment combining two or more embodiments is also an embodiment of the present invention.

Claims

1. A positive electrode composite precursor comprising a sulfur-based active material, a carbon material having pores, and at least one of an ion conductor and a modified body of the ion conductor, wherein the sulfur-based active material is present in at least a part of the inside and outside of the carbon material, and at least a part of the ion conductor and the modified body of the ion conductor covers at least a part of the sulfur-based active material.

2. The cathode composite precursor according to claim 1, which satisfies at least one of the following formulas (1) and (2) in the P2p spectrum in surface element analysis by X-ray photoelectron spectroscopy. I Ａ / I Ｂ >0.8 (1) I Ｃ / I Ｂ >0.8 (2) (In the formula, I Ａ is the signal intensity at position A where the binding energy is around 135.4 eV, I Ｂ is the signal intensity at position B where the binding energy is around 134.25 eV, and I Ｃ is the signal intensity at position C where the binding energy is around 133.0 eV.) 3. The above-mentioned I Ａ / I Ｂ and I Ｃ / I Ｂ The positive electrode composite precursor according to claim 2, wherein at least one of them is 1.0 or more.

4. The positive electrode composite precursor according to claim 1, wherein the element ratio C / P of carbon element and phosphorus element by surface element analysis by X-ray photoelectron spectroscopy is 20 or less.

5. The positive electrode composite precursor according to claim 1, wherein in the element mapping image analysis by energy dispersive X-ray spectroscopy of a scanning electron microscope image, the main component occupancy rate is 95.0% or more.

6. The positive electrode composite precursor according to any one of claims 1 to 5, wherein the total mass ratio of the sulfur-based active material, the ion conductor, and the modified body of the ion conductor to the carbon material is less than 5.

00.

7. The positive electrode composite precursor according to any one of claims 1 to 6, wherein the melting point of the ion conductor is 130°C to 450°C.

8. The positive electrode composite precursor according to any one of claims 1 to 7, wherein the ion conductor is a lithium ion conductive material containing one or more elements selected from lithium, boron, oxygen, and phosphorus or a precursor thereof.

9. The positive electrode composite precursor according to any one of claims 1 to 8, wherein the ion conductor contains phosphorus sulfide.

10. The positive electrode composite precursor according to any one of claims 1 to 9, wherein the ion conductor contains diphosphorus pentasulfide.

11. The positive electrode composite precursor according to any one of claims 1 to 10, wherein the sulfur-based active material contains elemental sulfur.

12. A method for producing a positive electrode composite precursor, comprising mixing at least one of a composite and a mixture of a sulfur-based active material and a carbon material having pores with a molten ion conductor.

13. The production method according to claim 12, wherein the composite of the sulfur-based active material and the carbon material having pores is mixed with the molten ion conductor.

14. The production method according to claim 12 or 13, wherein the total mass ratio of the sulfur-based active material and the ion conductor to the carbon material is less than 5.

00.

15. The production method according to any one of claims 12 to 14, wherein the melting point of the ion conductor is 130°C to 450°C.

16. The manufacturing method according to any one of claims 12 to 15, wherein the ion conductor is a lithium ion conductive material containing one or more elements selected from lithium, boron, oxygen, and phosphorus, or a precursor thereof.

17. The manufacturing method according to any one of claims 12 to 16, wherein the ion conductor contains phosphorus sulfide.

18. The manufacturing method according to any one of claims 12 to 17, wherein the ion conductor contains diphosphorus pentasulfide.

19. The manufacturing method according to any one of claims 12 to 18, wherein the sulfur-based active material contains elemental sulfur.

20. A positive electrode composite material containing the positive electrode composite material precursor according to any one of claims 1 to 11.

21. The positive electrode composite material according to claim 20, further containing a solid electrolyte.

22. A positive electrode containing the positive electrode composite material according to claim 20 or 21.

23. A lithium ion battery containing the positive electrode composite material according to claim 20 or 21, or the positive electrode according to claim 22.

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